Breastfeeding vs. Formula: Feeding and the Impact on Infant Sleep

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Sleep is essential to our daily life. As a new parent, you want to ensure that you and your infant are getting the best sleep possible. Friends might tell you that breastfeeding your baby will be the best way to ensure a peaceful night’s sleep, while another person may suggest formula feeding for the best slumber. Couple this with other information around how much sleep a baby should get, and feeding techniques and protocols can seem overwhelming.

Research surrounding formula versus breastfeeding and the impact on sleep is conflicting. In the case of breast milk vs. formula, it appears that some studies support both positions. This can add to the confusion. However, most studies do say something similar about infants and sleep: no matter what you feed them, their sleep will improve as they grow and get older.

There is a long-standing assumption that formula will promote longer sleep periods and less wakefulness during the night. Despite recommendations from the World Health Organization to breastfeed exclusively until a child is 6 months old, mothers in need of more sleep sometimes choose to introduce formula early. Is this rumor about formula true?

A study in 2013 found that breastfed babies woke more often than formula-fed babies. However, they had fewer breathing issues and were able to fall asleep faster. Breast milk naturally contains melatonin, a hormone associated with sleep. Infants cannot produce this hormone on their own and rely on the secretion in breast milk to help regulate their circadian rhythms.

Another study in 2017 found that three-month-old babies fed breast milk during the first few months of their life slept more during the night than their formula-fed counterparts. However, this study also found that the exclusively breastfed babies had a harder time sleeping by age 6 months than the babies who were fed formula.

Formula does not typically include melatonin. Therefore, some studies suggest that the presence of melatonin in breast milk means that breastfeeding increases sleep quality by decreasing colic and crying spells and helping the infant return to sleep quicker.

Infants are developing so quickly, and their sleep patterns reflect this. One study in 2015 showed that formula or breastmilk had little effect on the sleep/wake patterns of babies over the age of 6 months. Both breastfed babies and formula babies showed a decrease in nighttime wakings as they aged past 6 months. Ultimately, one group did not outperform the other in terms of sleeping longer.

A common assumption is that topping off your baby’s last meal with rice cereal or another heavier food before bed will increase sleep. This belief appears to be untrue, as research suggests that feeding additional solid food to your child will not decrease wakefulness during the night. Cereals or other foods should not be added to bottles for safety reasons.

It’s important to note that your baby’s stomach capacity is very small and therefore cannot hold a large volume of milk and that babies under the age of 4 months should be given no food other than breast milk or formula. While there is some evidence to suggest that formula takes longer to digest than breastmilk, your baby will still require frequent feedings due to the small size of their stomach, regardless of what option you chose.

Utilizing a hybrid feeding schedule does not seem to help your baby sleep through the night. While feeding your child more food before bed might reduce their hunger levels throughout the night, it doesn’t seem to impact their sleep patterns.

There is often the belief that babies wake in the middle of the night only due to hunger. This, however, is not entirely true. Evening routines, sleep schedules, and other factors specific to you and your baby impact their sleep.

Successful nights require more than just a good feeding. Regardless of if you chose to feed your infant breastmilk or formula, you can help them sleep longer by:

• Creating a sleep schedule and sticking to it
• Keep the room dark and comfortable
• Block out noise
• Set a specific time to get up
• Keep a sleep schedule to track sleep/wake patterns

While the research is inconclusive, it shows that overall, formula and breastmilk do not drastically differ in how they impact infants’ sleep/wake cycles. Research also shows that the common belief of “topping off” your baby with solid food before bed has little overall impact on the quantity of sleep.

Breast milk provides sleep-inducing hormones and appears to help with breathing and colic issues in infants. It is easier to digest, which may contribute to more frequent night wakings. On the other hand, formula is harder to digest and may help your baby sleep marginally longer. However, formula does not help your baby fall back asleep quickly as it does not contain sleep hormones.

The research does agree that infants will wake during the night regularly until about age 12 months regardless of what they are being fed. Studies show that maternal sleep patterns do not differ between breastfeeding or formula. As your baby ages, their sleep cycles will lengthen, allowing you to get better sleep yourself. Here are a few steps you can take to make the best decision for yourself:

• Talk to your doctor about your sleep and feeding concerns. Mothers experience a drastic decrease in sleep quality as well, and this can impact their overall health.
• Talk to a trusted friend
• Learn about infant sleep methods and how to implement them with your child

About The Author

Dr. Michael Breus

Clinical Psychologist, Sleep Medicine Expert

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Michael Breus, Ph.D is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. He holds a BA in Psychology from Skidmore College, and PhD in Clinical Psychology from The University of Georgia. Dr. Breus has been in private practice as a sleep doctor for nearly 25 years. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is also the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan, Good Night!, and Energize!

• POSITION: Combination Sleeper
• TEMPERATURE: Hot Sleeper
• CHRONOTYPE: Wolf

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